Succinic semialdehyde dehydrogenase deficiency (SSADHD) is a rare autosomal recessive disorder of γ-aminobutyric acid (GABA) catabolism caused by mutations in the gene coding for succinic semialdehyde dehydrogenase (ALDH5A1).
We present a patient with Rett syndrome (RTT; MECP2) and autosomal-recessive succinic semialdehyde dehydrogenase deficiency (SSADHD; ALDH5A1 (aldehyde dehydrogenase 5a1 = SSADH), in whom the current phenotype exhibits features of SSADHD (hypotonia, global developmental delay) and RTT (hand stereotypies, gait anomalies).
Toxicologic/transport properties of NCS-382, a γ-hydroxybutyrate (GHB) receptor ligand, in neuronal and epithelial cells: Therapeutic implications for SSADH deficiency, a GABA metabolic disorder.
Numerous metabolic perturbations unmasked in SSADHD include alterations in oxidative stress parameters, dysregulation of autophagy and mitophagy, dysregulation of both inhibitory and excitatory neurotransmitters and gene expression, and unique subsets of SNP alterations of the SSADH gene (so-called ALDH5A1, or aldehyde dehydrogenase 5A1 gene) on the 6p22 chromosomal arm.
A study in 2003 described 35 mutations of ALDH5A1 in 54 unrelated families, and the current study and systematic literature review identified nine additional novel mutations in eight unrelated families bringing the total number of unique mutations of ALDH5A1 resulting in SSADH deficiency to 44, and the 44 mutations occur from exon 1 to exon 10.
Inherited deficiency of SSADH results in accumulation of the neuromodulator γ-hydroxybutyrate (GHB), which likely contributes to some aspects of the neurological phenotype of SSADH deficiency (MIM #271980).
Therapeutic concepts in patients with SSADH deficiency and preclinical therapeutic experiments are discussed in light of data collected from research in Aldh5a1-/- mice and animal studies of GHB pharmacology; these studies are the foundation for novel working approaches, including pharmacological and dietary trials, which are presented for future evaluation in this disease.
Diagnosis of SSADH deficiency in our patient was established by demonstration of absent enzyme activity in isolated leucocytes, and was associated with a novel missense mutation (c.587G>A; p.Gly196Asp) in the SSADH coding sequence.
Elucidation of the precise fundamental mechanisms of the perturbation of the GABA(A)R-mediated function in SSADH(-/-) mice could lead to the development of novel treatment modalities designed to reduce the neurological morbidity in children with SSADH deficiency.
Succinic semialdehyde dehydrogenase deficiency: clinical, biochemical and molecular characterization of a new patient with severe phenotype and a novel mutation.
Mutational spectrum of the succinate semialdehyde dehydrogenase (ALDH5A1) gene and functional analysis of 27 novel disease-causing mutations in patients with SSADH deficiency.
Mutational spectrum of the succinate semialdehyde dehydrogenase (ALDH5A1) gene and functional analysis of 27 novel disease-causing mutations in patients with SSADH deficiency.
Mutation analysis in a patient with succinic semialdehyde dehydrogenase deficiency: a compound heterozygote with 103-121del and 1460T > A of the ALDH5A1 gene.